2007-2010 CAVE INVENTORY PROJECT IN WRANGELL SAINT ELIAS NATIONAL PARK AND PRESERVE

Alaska’s Wrangell-St. Elias National Park and Preserve (WSENPP) has extensive outcrops of Triassic Nizina and Chitistone limestone formations which overlie the Nikolai Greenstone. Throughout the Quaternary these limestones have been transformed into a karst landscape with some cave formation, interrupted by periods of glaciation. The caves and karst lands of the WSENPP have not been completely inventoried under the Federal Cave Resources Protection Act (FCRPA) which requires protection of significant caves on federal lands. To begin addressing this deficiency, the WSENPP funded surveys of three cave areas 1) The Nizina River and its West Fork 2) The upper western Kennecott watershed, and 3) Hidden Valley, a Kennecott river tributary in 2008.

Preliminary results indicate most of the WSENPP caves were poorly developed. This somewhat arid karst landscape in south central Alaska receives a mean annual precipitation of 1000-2000 mm/yr in contrast with the 1500-7000 mm/yr received in the more extensively developed southeastern Alaska cave and karst areas in the Silurian–Triassic limestones. Greater dissolution in a richer cave resource area occurred in the Hidden Valley region relative to the heavily glacierized areas of the Nizina and its West Fork rivers. One moderately developed cave system was inventoried within the Kennecott watershed. Numerous frost pockets formed by mechanical weathering were common in all areas. Few enterable and active underground water conduits were found during these surveys. Doline and grike intake areas at high elevation are now covered by glaciers. Most of limestone areas in the western Kennecott watershed had no surface drainage indicating the presence of subterranean conduits. Ancient structures likely formed by upwelling phreatic waters and later exposed by glacial erosion are now incidental caves unrelated to present karst processes. Small caves with wall solution features are relict features formed by ancient karst or hydrothermal systems that are no longer active.

A small mammal bone fragment recovered from one of the Hidden Valley caves was dated using conventional radiocarbon analysis and yielded a calibrated radiocarbon age of 170 +/- 40 years. Stable isotope analysis of the bone yielded 13C/12C values of -19.0 o/oo and 15N/14N values of +4.5 o/oo.